As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ARCING SOUND HEARD FROM OVERHEAD PANEL ACCOMPANIED MOMENTARILY BY FIRE LIGHTS IN APU FIRE SWITCH.(<P>REMOVED AND REPLACED ENG/ APU FIRE EXT MODULE PER B747 AMM 26-10-02. R/R CIRCUIT CARD A22 REF AMM 26-10-01. OPS TEST GOOD, NO DEFECTS NOTED AT THIS TIME. </P>)